In 1972, H. Kogelnik and C. Shank in Bell laboratory provided the principle and explored properties of distributed feedback laser (DFB) based on the coupled wave theory of electromagnetic field. In contrast to a Fabry-Perot laser with feedback mirrors, the DFB laser includes a periodic structure acting as a feedback cavity. The DFB laser has merits of high reflectivity, long gain length, strong wavelength selectivity, high reliability and low thresholds.
In the past decades, great developments have been achieved in the field of polymer lasers. In 1992, D. Moses et al. reported laser emission from xylene solutions of MEH-PPV with a high fluorescence-quantum yield efficiency comparable with Rhodamine 6G. In 1996, R. Friend et al. in Cavendish Lab of UK realized the emission of polymer microcavities under optical pumping conditions. In 1998, A. Heeger found that the thin film of BuEH-PPV can work as a polymer lighting emitting device with high quantum efficiency, high gain coefficient and low lasing threshold. Varieties of polymer lasers have been fabricated using simple techniques, such as flexible conjugated polymer lasers, hybrid polymer lasers, all-solid-state polymer lasers, circular grating polymer lasers, and photonic bandgap polymer lasers. However, practical applications demand miniaturization and lightweight designs of polymer lasers.